The Ionic Conducting Polymer gel Film(ICPF) can be driven by a low voltage (about 1.5 V) and has advantages in the less mass and fast response. A micro-robot moved at 3 mm/s velocity in the water can be actuated by the ICPF (21.6 mm×4.6 mm×0.2 mm). An image processing system is designed for detecting and controlling the movement and posture of the micro-robot,which consists of a CCD camera,an image interface card,a computer and a waveform generator. A movement and posture image sequence of the robot fish is captured by a CCD camera to obtain a binary image of each frame by the hue automatic threshold segmentation and boundary extraction based on the similarity target of in a short period. Then,the target location and movement direction are calculated by the circle detection using improved Hough transform. According to the target location and movement direction,the robot fish posture can be controlled by changing the voltage and frequency of ICPF and by using the waveform generator. Results show that system consumes 52 ms for processing a piece of picture in a Pentium 4 2.8 G computer with 1 G memory and achieves the real-time detection,tracking and control for the micro-robot fish.